We know that atoms are represented as letters. So, H means a Hydrogen atom, for example. Because molecules are just combinations of atoms, a molecule is represented as multiple letters. This is called the molecule's chemical formula.

The chemical name of the salt we use in cooking is Sodium Chloride. It is made up of 1 atom of Sodium (Na) and 1 atom of Chlorine (Cl). So, its chemical formula is just NaCl.